This invention relates generally to forceps of the rongeur or bone cutting type. It has long been an object in the art to provide simple, inexpensive forceps capable of easy disassembly and cleaning, and most importantly capable of safe and efficient operation. Prior patents issued in this art have proposed possible solutions. Typical of the prior art is the patent issued to De Vilbiss, U.S. Pat. No. 1,040,523, which provides a lever mechanism comprising a handle having two sides arranged to pivot towards one another about a central axis. On extensions of these handle members there is provided a jaw mechanism comprising a first movable jaw arranged to travel within a slot defined within a second movable jaw. Bone seized between the jaws is pulled within the slot as it is cut. A problem associated with this and other mechanisms in the art is that uncontrolled force is applied to the bone surface surrounding the cutting area, such that possible bone breakage and splintering may occur. If operating near the spinal cord, possible nerve damage may result. Further, bone chips cut from the bone structure are not well contained by the instrument and contamination of the wound may result. Finally, with the pivot placed between the jaw mechanism and the lever handles limited mechanical advantage is available, making the instrument tiring to use.
Accordingly, it is the primary aim of the present invention to provide an approved forcep or rongeur for cutting bone wherein the bone chips, once severed, are safely contained within the instrument and held therein until selectively ejected.
It is a further object of the present invention to provide a jaw-like mechanism wherein bone chips are immediately deposited within the capturing instrument as they are cut.
It is also an object of the present invention to eliminate uncontrolled forces in and about the cutting area to avoid possible bone breakage and splintering beyond the cutting area.
It is also an object of the present invention to modify the mechanical leverage to provide improved mechanical advantage for the device and to provide better control during operation.
Briefly stated there is provided an improved forcep or rongeur having a jaw mechanism comprised of a barrel member having a honed cutting edge on one extremity thereof and having a shaft member located within and arranged for reciprocal motion. On the shaft member there is provided a plate member attached at one extremity to trap bone against the cutting edge. A lever mechanism is provided having paired handle levers joined by a pivot and having the barrel and shaft members attached to the handle levers between the handle portion and the pivot. On the shaft member there is further provided a cavity arranged to slide within the barrel progressively as the cutting operation proceeds, gradually drawing severed bone within the capturing cavity, allowing for a cutting action rather than a crushing action, thereby relieving pressure on the plate member and thus reducing the possibility of breaking said member while cutting bone structures.